Heat Balance and Transfer in Men and Women Exercising in Hot-Dry and Hot-Wet Conditions
Abstract
Sex-related differences in heat balance and transfer were studied in nine female and ten male heat-acclimatized subjects exposed to hot dry (HD) conditions (49 deg C, 20% rh; 54 deg C, 10% rh) and three hot wet (HW) conditions (32 deg C, 80% rh; 35 deg C, 90% rh; 37 deg C, 80% rh). Exposures lasted 120 min: 10 min rest, 50 min walk, 10 min rest, 50 min walk. Walking speed was 1.34 ms (expn -1) (level), and for 49 deg C 20% rh in addition. 1.34 ms (expn -1), 5% grade. No sex-related differences were found in metabolic heat production (M), nor in heat exchange by radiation and convection (R + C) or evaporation (E), when expressed per unit body weight (wt). However, E per unit body surface area (A sub D) was lower in females by 9-13% (P<0.05 in all HD conditions and for the 32 deg C, 80% rh condition) due to their lower M A sub D, and 4.5% lower (R + C) A sub D in HD. Core-to-periphery heat conductance was similar in both sexes despite a lower core-to-skin temperature gradient for women in HD. It was suggested that women have an advantage over men in heat transfer particularly in HW because of their higher A sub D /wt. The disadvantage of a high A sub D /wt at high HD environmental temperatures is diminished by a higher skin temperature, thus reducing (R + C) heat gain. The net effect is to require lower evaporative cooling for women in both HW and HD environments.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1981
- Accession Number
- ADA107004
Entities
People
- Barbara A. Avellini
- Kent B. Pandolf
- Nancy A. Pimental
- Ralph F. Goldman
- Yair Shapiro
Organizations
- United States Army Research Institute of Environmental Medicine